To kill cockroaches, take a glass jar and put some peanut butter in the bottom of the jar. Put a good smear of vegetable oil around the inside lip of the jar to make it very slippery. The roaches smell the peanut butter, go in after it and can't get out (they slip and fall back into the jar). When the jar has a few roaches in it, cap it off with the lid and put it in the sun to kill them. Then throw the whole lot in the garbage. This will effectively reduce the cockroach population in a short time. If they lay egg cases while they are dying (as they do in traps), it's all contained in the jar.